Gliederung

Background: Proton radiotherapy can be prescribed similarly to photon radiotherapy to achieve comparable disease control rates. The chief advantage of protons for a given prescription dose is to spare acute and late toxicities by decreasing the amount of normal tissue receiving radiation. We have treated 29 pediatric Ewing's sarcoma patients with proton radiotherapy at the Burr Proton Facility and report the preliminary clinical outcomes including late effects.

Materials and methods: 29 children with Ewing sarcoma treated at the Francis H. Burr Proton Facility between April 2003 and April 2009 and were included in this study. Medical records were retrospectively reviewed.

Results: Twenty-nine children (13 males and 16 females) were treated for Ewing's sarcoma with proton irradiation and standard chemotherapy, with or without surgery. Median prescribed dose was 54 CGE (range, 45–59.4 CGE). At a median follow-up of 21.7 months from the start of radiation therapy (range, 30 days to 6 years), crude rates of local control, progression-free survival, and overall survival were 93.1%, 79.3%, and 89.6%, respectively. The median age at proton therapy was 10.8 years (range, 1.8–21.0). Location of tumors included the pelvis (4), trunk (15; 14 involving the vertebrae), head and neck region (6), and the cranium (6). There were no extremity lesions.

At the last follow up, four patients (14%) were alive with disease, two patients (7%) have died of disease and one (3%) for second tumor, twenty two (76%) showed no evidence of disease. Proton therapy was acutely well tolerated with a range of mild to moderate skin reactions. To date, documented late effects include scoliosis/kyphoses in 4 patients, 3 most likely attributable to surgical laminectomy, 1 mild limb length discrepancy requiring no intervention, radiation induced skin changes in 4 patients (3 hyperpigmentation, 1 with telangectasias), 1 hypothyroidism, 1 unilateral high frequency hearing loss, 1 growth hormone deficiency, and one patient developed ptosis with chronic corneal erosion (who received radiotherapy for a gross Ewing's of the orbit). There were 4 secondary malignancies, 3 AMLs and one myelodysplastic syndrome. The hematologic malignancies/disorders are known risks of etoposide exposure.

Conclusions: Proton therapy was well tolerated without unacceptable adverse events. Although the follow up is short, failures are typically within 2 years and these early outcomes compare favorably with the literature. Longer follow-up time is needed to more fully assess tumor control and late effects of treatment including functional and cosmetic outcome.